A flammable gas explosion is an analyzed hazard and gas detection/shut off is a safety significant control system that requires a limiting condition for operation (LCO). The rigor of the evaluation of flammable gas systems was inadequate. There…

Recommended Actions:

• The recommended safe storage time for AHF is two years. Contact the vendor for pick up and disposal for cylinders more than two years old. (Unused gas should also be returned, even if it has been less than two…

All chemicals, including gases, should be clearly labeled and expiration dates (if applicable) identified. Incidents are more common when incompatible chemicals are mixed or when chemicals are stored/transferred using incompatible equipment.…

The following corrective actions have been taken:

• The non-return valve was dismantled, cleaned, and tested. Following positive testing, the system was restarted and pressurized without any further malfunctioning.
• The hydrogen…

Because the bottle was located outside at the time of the event, and the hydrogen did not find a source of ignition while venting through the relief valve, nothing serious happened. The failed regulator was replaced and operations continued.…

LESSONS LEARNED:

1. Compressed gas cylinder caps can be very difficult to open as rust often occurs in the threads.
2. There are wrenches specifically designed to remove…

1. A hydrogen tube pressure indication system needs to be developed that is robust enough to withstand an accident, indicates hydrogen pressure regardless of valve position, and would be visible from a safe distance during an accident situation…

Incident investigation findings for corrective actions were:
1. Install a valve after the regulator as an added precaution.
2. Clean the coupler at the end of the hydrogen delivery tube after each use to ensure that any catalyst residue…

Hazard analysis should consider potential leak locations, potential ignition sources in the vicinity, and the potential for accumulating flammable gases in that area.

Users should leak-check all cylinders upon installation. This event…

1. Revise fire protection operations surveillance tests to include a maximum of 110% of the agent net weight to prevent over-filled cylinders from being placed in service.
2. Identify cylinders currently in service that exceed the 110…

• The fuel cell vehicle that was involved in the accident has been retired. The fuel cell power plant from that vehicle has been removed and is being used in another fuel cell vehicle.
• The fuel cell vehicle accident reinforced the…

Several recommendations were outlined by the investigating committee to govern future operations of the hydrogen compressor in the synthetic liquid fuels laboratory:

1. Install a cutoff that will shut down the compressor when the…

A tool is provided for removing the cylinder cap that cannot contact the valve.

Several best practices resulted from this incident and will be implemented if similar circumstances present themselves in the future.

• Close bay door.
• Keep within proximity of bay.
• Be aware of other bays…

Several procedural and design changes should be considered for the future:

1. Replace the use of pure hydrogen with a 95:5 mixture of nitrogen and hydrogen to reduce the possibility of an explosive atmosphere occurring. Laboratory…

The ignition of the fireball could have been caused by any of the following mechanisms:

• The inverse Joule-Thompson effect of hydrogen (i.e., heating upon expansion)
• Some of the oil and light ends were above their auto-…

1.  Combustible gas detectors calibrated for hydrogen can falsely report hydrogen alarms due the presence of other gases the detector may pick up, such as carbon monoxide from engine exhaust or other sources. Since this event occurred, two…

A hydrogen release of this type is a significant event. The event highlighted a number of procedural contributing factors that will influence the manner in which these fuel cell systems will be serviced in the future. A complicating factor in…

Procedures for safe handling of compressed gas cylinders, marking design of gas cylinders and connecting lines, and arrangement of cylinders were reviewed and modified as necessary. The spectrometer was returned to the manufacturer for a careful…

1. The hydrogen supplier installed a fire-resistant material board adjacent to the high-pressure hydrogen storage banks to prevent any potential jet flames from affecting adjacent high-pressure cylinders for several minutes. The 0.25 mm…